Andrea Caputo, a physicist at CERN, argues that gravity remains the only confirmed way we detect dark matter, since none of the proposed particle interactions with the Standard Model have been observed directly. Speaking at the Institute for Advanced Study's astrophysics seminar in the Bloomberg Lecture Hall, he walks through dark matter candidates that may only ever be accessible through gravitational effects, showing how dwarf galaxies and ultra-faint dwarf galaxies serve as testing grounds for these models. He extends the discussion beyond dark matter to light particles that could exist while staying completely hidden from ordinary matter, and explains how gravitational-wave detectors like LIGO and Virgo, along with precision interferometry instruments such as GRAVITY, might offer new ways to catch signs of such elusive particles. The talk runs just under an hour and is pitched at a research-seminar level, built around open problems in current astrophysics rather than settled textbook material.